Modified the plugin's format function to support timezone formatting tokens (z, Z, ZZ)

Hey
 
I (re)implemented the timezone formatting tokens in this plugin. This plugin provides a the timezone information need to properly format these tokens, yet the format function didn't take advantage of the additional data. Now the timezone formatting tokens are processed by the plugin and inserted as an escaped substring into the original formatting string. 

I also added concat and min targets to the grunt file and expanded the module exposing code to support browser usage. I tried to follow the pattern used by moment.js and it's lang files with moment-timzone.js and it's timezone files.

-Andrew